For the past year, Fast Company has interviewed innovators across several industries and geographies. This slideshow offers a shortcut to each of their stories, but unfortunately there is no shortcut to replicating their success. You won't find some magical strand of DNA that links these 28 individuals, they are all radically different from one another. But you will find that they often have a genuine curiosity about why things work the way they do, and a deep passion for their work--which they believe is having a positive impact on the world.

Who should I include in 2012's Innovation Agents series? Tweet your nominations to me (@noahr) using the hashtag #InnovationAgents.

Adam D'Angelo, Charlie Cheever, Rebekah Cox, Quora

It's not just what gets answered here, but who's doing the answering. No matter what your question, Charlie Cheever, Adam D'Angelo, and the Quora team are confident you'll find an expert answer on their site.

Dr. T cofounded the technology giant that is National Instruments out of his garage more than 35 years ago with a $10,000 loan. NI's software and hardware are behind everything from robotics and smart cameras to medical diagnostic equipment. Next stop, commercial space flight.

Heather Knight, a key member of the Syyn Labs League of Extraordinary Nerds, curates public performances with automatons, and believes that her robots can change the world for the better. Watch the video to find out how.

"We have everyone you can imagine against us," says Jack Dorsey, the CEO of mobile credit card pay startup Square and cofounder of Twitter. But he is not cowed by fact that his startup is competing against banks with far more money to spend on pushing their products to market. Because by allowing design and engineering to lead his strategic decisions, Dorsey knows that he can out-innovate everyone else.

"It's about being shameless and relentless and hustling for the first users and for the first partners," says Best, the founder and CEO of DonorsChoose.org. "That takes both sort of an energy and a humility."

Frustration can be a great motivator. Just ask Alastair Mitchell, the CEO and cofounder of Huddle, a set of tools for collaborating with teams of people spread across different geographies and in multiple languages.

Sasha Dichter, the director of business development for Acumen Fund, wants you to know that social impact investing is anything but a crock. He talks to Fast Company about making a difference for global social good.

User-generated content, social media, and digital photographs have all led to a boom where you might least expect it: On paper. Under Vyomesh Joshi's guidance over the last eight years, HP's Imaging and Printing Group revenue has grown from $19 billion to $25.8 billion, and its operating profit has doubled.

For Nusrat Durrani, senior vice president and general manager of MTV World, the connective tissue that binds cultures and countries is music. It also provides the insistent beat that drives MTV’s newest multi-platform global music brand, MTV Iggy, a channel that aims to bring artists and pop culture from around the world to America.

Mikkel Svane of Zendesk managed to grow his cloud-based help desk software startup in the wake of customer complaints. "The best thing a company can do," he tells us, "is embrace its mistakes." You listening, Netflix?

As CEO of Novartis, Europe's second largest drug company, the former competitive swimmer Joe Jimenez won't rest until he snags the top spot. The key: innovative products, expansion into new markets, and good old-fashioned team building.

Traditional ad agencies aren't going away, but according to MOFILM CEO Jeffrey Merrihue, MOFILM's crowdsourced mobile video content and its community of creative filmmakers are going to give them a run for their money.

Of the many labels pegged to Lady Gaga--pop star, fashion icon, provocateur--here's one title you might not expect to see on her résumé: creative director at Polaroid. The "Bad Romance" superstar teamed with the camera and eyewear company earlier this year. Two of the three "Grey Label" products she helped develop have yet to come to market; Polaroid says the Gaga Goggles are still in development.

This year, Harman CEO Dinesh Paliwal launched the first social-networking automobile so drivers can get Facebook, Twitter, texts, and Internet connectivity and still keep their hands on the wheel and their eyes on the road.

By the end of this year, there should be 15,000 Chevy Volts and Opel Amperas on the road, and hydrogen-powered vehicles aren't far behind. Where to power up all those electric cars? Britta Gross, GM's director of global energy systems and infrastructure commercializaion, is working on the solution.

Meet The Innovation Agents

For the past year, Fast Company has interviewed innovators across several industries and geographies. This slideshow offers a shortcut to each of their stories, but unfortunately there is no shortcut to replicating their success. You won't find some magical strand of DNA that links these 28 individuals, they are all radically different from one another. But you will find that they often have a genuine curiosity about why things work the way they do, and a deep passion for their work—which they believe is having a positive impact on the world.

Who should I include in 2012's Innovation Agents series? Tweet your nominations to me (@noahr) using the hashtag #InnovationAgents.